Chances are, if you’re a car owner, you’ve heard of oil consumption. You might even know that it’s bad for your engine. But what is oil consumption, exactly? Oil consumption is when the engine oil enters the combustion chamber, and is burned off rather than returned to the oil pan for further lubrication. Small amounts of oil consumption is common. However, if your car has lost significant amounts of oil before the next oil change, then this is an indication of excessive oil consumption. If ignored, excessive oil consumption will do major damage to the vehicles engine.
In this post, we’ll answer the most commonly asked questions and more about oil consumption. We’ll also help you determine whether or not your car has a problem with oil consumption. So read on to learn everything you need to know about this serious issue!
When is Oil Consumption a Problem?
The issue of oil consumption is something that can be quite frustrating for car owners. More often than not, manufacturers don’t provide uniform guidance on this issue. As a general rule however, if an engine requires a quart of oil every 3,000 miles or less, that could be a sign of excessive oil consumption. This level of oil consumption is a problem that will damage valve guides, piston rings or even cause catastrophic engine failure.
What Causes Oil Consumption?
The most common reasons for engine oil consumption are worn valve stems, bad seals, and worn or cracked piston rings. All of these can allow oil to seep into combustion chambers of the engine.
What is Excessive Oil Consumption?
Excess oil consumption is any oil consumption above an acceptable range during normal operating conditions. Each engine will have a natural and acceptable amount of oil consumption, which you do not need to worry about. Any consumption above these given levels is excess consumption and should be addressed.
Keep in mind that the engine of your car can easily be damaged by excessive oil consumption. If ignored too long, the problem will do major damage and leave you with either a overheated or malfunctioning vehicle.
What Are the Effects of Engine Oil Entering the Combustion Chamber?
Engine oil is a hydrocarbon, and when presented in the combustion chamber during the combustion cycle, it ignites and burns as any other hydrocarbon. However, due to the chemical nature of oil it is more viscous and denser than gasoline. This means it burns slower and generates heat over a longer period of time. Because of these characteristics, engine oil contributes practically nothing to the combustion part of the cycle, and only generates heat in the exhaust system.
It does consume some of the oxygen in the combustion chamber, thereby reducing both ignition and combustion efficiency. This in turn increases emissions, which causes the fuel management system to introduce a different and most often non-optimal fuel-to-air ratio during the next cycle.
Optimum combustion depends on the correct fuel/air ratio in order to provide a near stoichiometric mixture. The oxygen sensors monitor unburned oxygen in the exhaust gases and send this information to the engine control module, which then uses this information to determine if the fuel mixture is rich (too much fuel) or lean (not enough fuel) and adjusts the fuel/air mixture as necessary. The oxygen sensors also measure oxygen levels after the exhaust reacts with the catalytic converter, to help the engine run efficiently and to minimize emissions.
The catalytic converters are emission control devices designed to convert toxic pollutants contained in exhaust gases to less toxic pollutants by catalyzing a redox reaction (oxidation or reduction).
Effects of Excessive Oil Consumption
Worn valve stems, guides and seals can all allow oil to seep into combustion chambers. This is often a result of prematurely worn components that have been neglected over time–the byproduct being burnt fuel with little power resulting in low engine performance.
Long-term uneven wear on different engine parts could lead up an even bigger problem down the road–such as seal failure leading more serious issues like major engine damage.
Why No Recall for Oil Consumption?
The National Highway Traffic Safety Administration has declared that they will not recall a car due to excessive oil consumption.
Oil is an essential, yet often overlooked part of the engine. If you don’t keep your oil at the right level your car will run poorly or stop running completely in some cases. The best way to ensure your engine doesn’t break down is to take preventative measures and keep an eye on the oil level. Have you checked your car’s oil lately?
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Last Updated on March 31, 2022
Loves anything with a motor and wheels.
Christopher is an automotive technical writer. When he’s not at the local autocross event, he can often be found working on one of his cars. Specializes in automotive class action law, industry trends, and automotive maintenance. Email me direct, or learn more about us
2 thoughts on “What is Oil Consumption and When is it Bad For Your Engine.”
L HernandezApril 27, 2022 at 3:42 pm
I had an issue with my car engine where it went into limp mode. Luckily I wasn’t on a freeway, but I did have to leave my car for a bit while finding someone to transport car to dealer as I didn’t want to risk damaging the engine further. I found out there was a software issue and knock sensor needed replaced due to a recall. Car got towed to the dealer for repair. I have also had issues with strange noises coming from engine area.
LillianMarch 17, 2023 at 9:34 am
I’m the owner of a Hyundai Tucson (2018) and came home today learning my car may be having oil consumption problems. I purchased it off the lot and have 6 payments left and 67K (warranty expired).
I see there is litigation in California – unresolved – on this same circumstance. Do you know if Minnesota has any filings? A google search only provides info on the CA case. I’ve filed a complaint with Attorney General and in the meantime, wonder how to be safe with my drive?